The typical approach for drying walls damaged by water is to install air movers (e.g., air fans) directing the air flow towards the affected areas. The air inside the room is sometimes conditioned with heating and/or dehumidification equipment to improve drying. Such configuration is not optimal in terms of energy consumption and drying time. Often, restoration is not successful, mold appears and building owners need to reconstruct.
There is a need for fast drying (typically under 48 hours for drywall structures) to avoid rebuilding, to reduce the impact on business interruption and to reduce the risk of cross-contamination. Furthermore, proper decontamination measures need to be addressed when required.
Different methods and systems have been proposed over the years to deal with these situations. One approach suggests the use of directional drying fans in order to direct the air flow where needed. For instance, U.S. Pat. No. 7,331,759, incorporated herein by reference, relates to an axial drying fan especially conceived for directing air flow to specific locations such as to corners at the intersection of wall/floor
Another tactic is to use heat exchangers in order to transfer part of the energy (heat) from the warm (and humid) air in the building before replacing it with the dry (and cold) air from the outside. For instance, U.S. Pat. No. 6,457,258, incorporated herein by reference, discloses a portable drying system mounted on a trailer. The system uses a counter-current heat exchanger to transfer part of the heat from the exhausting air to the entering air in order to increase temperature. The system further heats the entering air with a propane heater. U.S. Pat. No. 6,662,467, incorporated herein by reference, presents a similar system but adapted to elevated buildings. The air is heated to 125° F. (52° C.) and relative humidity is drawn to 5% using a propane heater. U.S. Pat. No. 2006/0189270, incorporated herein by reference, further proposed to combine the heat exchanger with a building positive pressurization and controlling the exiting flow of air to maintaining the desired positive pressure inside the building. In such a way, humid air from inside the building will flow through cracks and openings to the outside carrying humidity. Air from the outside is conditioned (dried and/or heated) before flowing to the inside. U.S. Pat. No. 2006/0185819, incorporated herein by reference, proposes a portable heat exchanger driven by a fan. Outside air is first cooled to remove humidity and then heated-up before entering the treated room. In all these cases, drying achieved by venting the affected rooms with large volumes of air being moved around and as a result, the building cannot be occupied during the drying procedure.
Injection systems have also been proposed with the purpose of substantially reducing the volume of air to be treated, which is more convenient when dealing with cavities such as walls and ceilings. For example, U.S. Pat. No. 8,468,716, incorporated herein by reference, discloses an injection drying system comprising a blower to which a plurality of flexible hoses are connected at one end and inserted into the wall at the other end. Pressurized air enters the wall cavity to speed up drying. U.S. Pat. No. 5,155,924, incorporated herein by reference, proposes an injection system specifically conceived for tongue-in-groove flooring. A set of diverters are provided for drying inside walls, floors and ceilings. The injection system combines the use of a dehumidifier and/or a heater as well as an exhaust conduit to reduce humidity before reinjecting air into the treated areas. U.S. Pat. No. 5,408,759, incorporated herein by reference, discloses a device comprising a flexible/expandable bag (air impermeable fabric or sheet material) with several air conduits adapted to be inserted into holes in the wall, forcing air from a blower device into walls cavities. Several bags can be inter-connected for large areas. U.S. Pat. No. 5,893,216, incorporated herein by reference, proposes an air distribution unit having several conduits of varying cross-section and length with nozzles attached in order to be inserted into the wall through perforated holes. The unit can inject air into the cavities and/or extract air form it. Small holes need to be drilled into the walls and repaired after drying. U.S. Pat. No. 6,647,639, incorporated herein by reference, discloses an improved forced air system for drying walls, which is driven by a blower in an open or closed loop configuration and operated in positive (injection) or negative (vacuum) pressure. The system uses injectors with an innovative locking tab mechanism and anti-clogging system. U.S. Pat. No. 6,886,271, incorporated herein by reference, extends the use of this system for floor drying by connecting the injectors to a floor plate. All these systems work on the air injection principle which require making holes on walls that need to be repaired after drying.
Alternatively, other methods preconize the use of existing holes in the wall in order to avoid perforating the walls. For instance, U.S. Pat. No. 5,761,827, incorporated herein by reference, discloses a process by which pressurized air is injected into hollow walls through existing holes around water supply piping for toilets, eliminating the need to drill new holes and repair them after drying. U.S. Pat. No. 5,555,643, incorporated herein by reference, describes an apparatus for injecting (or extracting) air to (or from) a wall cavity through electrical boxes, which provide access to (portions) of the wall cavities. U.S. Pat. No. 8,978,270, incorporated herein by reference, presents a method for drying a wall cavity also through light switches of power outlets. These systems are however limited to the wall cavity areas that can be reached from the existing holes locations.
Yet another injection approach consists on targeting interior layers of sheathing for the specific case when moisture locates on the outside side of sheathing, not easily accessible from the inside. U.S. Pat. No. 5,960,556, incorporated herein by reference, discloses a system for drying interior layers of sheathing in narrow wall spaces. It uses nozzles with circumferential orifices that, once they are inserted into the wall structure through proper holes perforated for this purpose, face the targeted wall spaces between layers.
Besides the drying methods, there have also been some efforts to develop control and monitoring software to assist the drying procedure. U.S. Pat. No. 9,015,960, incorporated herein by reference, discusses a drying apparatus comprising a heating system operated to rise temperature to the desired level, a conduit to exhaust humid air out of the room when required, and a set of sensors to control temperature and humidity within the treated room. The apparatus works continuously until the optimal humidity is reached. U.S. Pat. No. 7,403,126 discloses an apparatus, system and method to provide drying procedure information through a user interface. U.S. Pat. No. 8,006,407, incorporated herein by reference, presents a drying system that provides enhanced drying through the use of remote sensors and control devices. U.S. Pat. No. 2006/0185838, incorporated herein by reference, discloses a method to control humidity through the use of heat exchangers comprising heating elements that operate when needed to reduce the relative humidity of the air entering the dried space.
Furthermore, when a structure is affected by water damage, possible contamination by molds is an additional concern besides drying. Molds spores are present everywhere, inside and outside buildings, and normally do not constitute a problem for human health or materials integrity. However, when favorable conditions (nutrients, temperature and humidity) are met, mold spores that have settled inside a building, for instance inside wall cavities, can grow at a fast pace. Therefore, a goal of water damage restoration is to dry and also to decontaminate the affected structures when needed to avoid rebuilding, which also implies a loss in time, money and user comfort.
In this sense, U.S. Pat. Nos. 5,408,759 and 5,960,556, both cited before, also mentioned the possibility to inject deodorants, disinfectants, fungicidal or ‘other treatments’ into the wall cavities. U.S. Pat. No. 7,357,831, incorporated herein by reference, proposes a combined approach to control humidity and mold through a heat exchanger (similar to the ones described above) and to add HEPA filters and UV lights to kill mold spores flowing in the air stream. U.S. Pat. No. 6,327,812, incorporated herein by reference, proposes a method of killing organisms and removing substantially the remains from the treated enclosure. It is based on heating-up the building surfaces to temperatures between 120-300° F., supposedly killing several microorganisms (mold, insects, bacteria, etc.). The combined use of ozone is preferred to increase effectiveness. U.S. Pat. No. 6,892,491, incorporated herein by reference, further improves this system by creating a negative pressure within the treated space and by increasing the air temperature heating range to 110-400° F. U.S. Pat. No. 2005/0066537, incorporated herein by reference, discloses a system for wall cavity decontamination by injecting and/or extracting air or biocides. The method includes an evacuation phase (to remove existing contaminants) that can be performed in extraction, injection or close-loop modes, a decontamination phase that is performed by exposing the contaminants to microwave radiation and/or biocides, and a lock-down phase to trap the remaining (non-viable) contaminants into the cavity.
In view of this, there remains a need in the art for a system for wall restoration after water damage that is compact, easy to use, more efficient and safe, that provides the possibility to effectively dry structures (e.g., wall structures) and decontaminate them when required.